Photothermal inactivation of heat-resistant bacteria on nanoporous gold disk arrays

A rapid photothermal bacterial inactivation technique has been developed by irradiating near-infrared (NIR) light onto bacterial cells (Escherichia coli, Bacillus subtilis, Exiguobacterium sp. AT1B) deposited on surfaces coated with a dense, random array of nanoporous gold disks (NPGDs). With the use of cell viability tests and SEM imaging results, the complete inactivation of the pathogenic and heat-resistant bacterial model strains is confirmed within ~25 s of irradiation of the NPGD substrate. In addition to irradiation control experiments to prove the efficacy of the bacterial inactivation, thermographic imaging showed an immediate averaged temperature rise above 200 °C within the irradiation spot of the NPGD substrate. The light-gated photothermal effects on the NPGD substrate offers potential applications for antimicrobial and nanotherapeutic devices due to strong light absorption in the tissue optical window, i.e., the NIR wavelengths, and robust morphological structure that can withstand high instantaneous thermal shocks

Alignment and actuation of compliant nanostructures and diffractive optics by inter-nanomagnet forces

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (p. 125-129).This thesis presents a novel method to stretch flexible nanostructures by nanomagnets interaction forces. We discuss the ability of different types of nanomagnets to distort several types of structures in two different cases. In the first, this method is applied for precise self-alignment of nanomembranes with applications in three-dimensional nanostructures manufacturing as well as distortion and patterning errors correction in a promising unconventional way. The second application addressed in this work shows the ability of nanomagnets to tune diffractive optical elements through deformation and actuation of nanostructured freestanding beams such as in a diffraction grating. This actuation combines the advantages of both analog and digital tuning techniques. For both applications, theoretical work, simulations, fabrication and experimental results demonstrating the promising power of nanomagnets over structural rigidity are presented.by Martin Deterre.S.M